Without limiting the scope of the invention, its background is described in connection with Carbon nanotubes (CNTs).
Carbon nanotubes have novel electrical and mechanical properties with potential biological applications ranging from sensors to tissue supports to artificial muscles (1). Various agents, e.g., surfactants (ref. 2 and references therein), polymers (refs 3 and 4, and references therein), polypeptides (5, 6 and references therein), and nucleic acids (7, 8)) have been used to disperse CNTs, however, two major hurdles exist that limit the usefulness of CNTs in many applications. First, current preparative methods for CNTs generate heterogeneous nanotube mixtures that can vary in length, diameter and electronic type (semiconducting, semimetallic and metallic). This heterogeneity ultimately limits the utility of the CNT materials. Recent work on the length (4, 9-13), diameter (7, 8, 14) and concomitant length and diameter (15) separation of CNTs, however, has provided important advances in the area of nanotube purification. Second, unmodified CNTs are very hydrophobic, readily aggregate, and are therefore difficult to interface with biological materials. Detergents like sodium dodecyl sulfate (SDS) that are commonly used to solubilize CNTs in water would likely disrupt cellular membranes and are incompatible with many biological applications, while covalent modification of CNTs with soluble moieties (16, 17) interferes with CNT properties.
What are needed are compositions and methods for the isolation, separation, characterization and functionalization of CNTs. These compositions and methods must be highly selective, rapid and inexpensive. Furthermore, the compositions and methods should be made from easily available materials that are not harmful to the environment. In fact, in some cases it will be very useful to use these compositions and methods to isolate and even chelate CNTs.